Windows: Description and Operation

Each power window is connected to a permanent magnet motor. The motor raises or lowers the glass when voltage is supplied to it by a door module. The direction the motor turns depends on the polarity of the supply voltage provided by its associated door module. The two front doors have their own separate modules. The rear seat contains a single module, which controls both rear power windows.

A serial digital communications link, called the Simple Bus Interface (SBI), is used for communications between door modules and the drivers door power window switches. The use of serial digital communications allows the use of a single wire to convey switching information between the Driver Door Switch and the Driver's Door Module. This serial communication is also used to transmit switching information from the drivers door module to the other two door modules.

The door modules apply battery voltage of the correct polarity to the respective window motor when any local, or Driver's Door Switch (DDS), UP switch is operated, driving the window up. Battery voltage is applied to the respective window motor in the opposite polarity when any local, or DDS, DOWN switch is operated, driving the window down.

Driver Door Module (DDM)
The DDM directly controls the driver's door window motor and the express down window feature. The DDM sends window UP/DOWN messages received from the DDS to the Passenger Door Module (PDM) and Rear Door Module (RDM) modules over the SBI line. The DDM also contains a Class 2 data link which communicates with other vehicle system modules. The LH front power door locks and power outside rear view mirror are also controlled through the DDM.

Passenger Door Module (PDM)
The PDM controls the passenger's door window motor. The PDM controls the passenger's door window directly from the RH Front Window Switch or from instructions over the SBI. The RH front power door locks and power outside rear view mirror are also controlled through this module.

Rear Door Module (RDM)
The RDM controls both rear door window motors. The RDM controls the rear windows directly from the rear door window switches or from instructions over the SBI.

Driver Door Switch (DDS)
The DDS provides switches for controlling all of the power windows. The DDS also has a lockout button, which the driver can use to prevent the other window switches from functioning. The DDS passes switching information to the DDM by way of the SBI. Battery voltage and ground are applied to the Drivers Door Switch from the Drivers Door Module through circuits 1729 and 226 respectively.

Simple Bus Interface (SBI) Serial Data Link
The SBI is a serial data link. This serial data link replaces vehicle cables between the various door modules with a single wire. The same amount of information is sent by multiplexing (time-sharing) data to and from each device over that wire. The serial data signals are referenced to ground. If the SBI is lost, both the RDM and PDM will go to sleep. With the RDM and PDM asleep, no power window operations are possible.

Express Down Window Operation
The express down window function is a driver's window only standard feature that allows the LH front window to be fully opened by momentarily pressing the LH front window DOWN switch to the second detent. Express down travel may be stopped at any position by momentarily pressing either the UP or DOWN switch.

Window Switch Operation
When any Drivers Door Window Switch is pressed, a SBI serial digital message is transmitted from the DDS to the DDM.

If the passenger or either rear window switch was pressed, an SBI message, relating the switch operation, is transmitted from the DDM to either the PDM or RDM as appropriate. All of the window motors are directly controlled by their respective door modules.

If the a drivers window switch is pressed, the DDM will apply battery voltage of the correct polarity directly to the LH front window motor, driving the window up or down.

Each window motor is protected by an electronic circuit breaker. If a window switch is held too long with the window obstructed or after the window is fully up or down, the circuit breaker opens the circuit. The circuit breakers have Positive Temperature Coefficients (PTC) and reset automatically when voltage is removed from the motors.